Rabbit Flashcards
Name the labeled structures
Alimentary tract from a mature rabbit, illustrating the
prominent gut-associated lymphoid tissue (GALT), including a Peyer’s
patch (A) in the wall of the ileum, the sacculus rotundus (B) at the
terminal ileum, the cecal tonsil (C) in wall of the proximal cecum, and
the cecal appendix (D) at the terminus of the cecum.
Name the tissue type and common cell type present.
GALT from a normal mature rabbit, depicting the
common presence of histiocytes filled with refractile particulate debris
within the follicular center.
Name the structure
Pulmonary artery of a normal rabbit. Pulmonary arteries
are highly muscular, which can be misinterpreted as muscular
hypertrophy.
Describe the structure and its incidence
Female reproductive tract of a normal doe, depicting the 2
separate cervices, which is typical for this species. The uterus is
bicornuate, with 2 separate horns.
Name the tissue, describe the lesion, name the cause
Integument from a rabbit with leporid herpesvirus 4
infection, depicting necrosis of the epidermis and papillary dermis with
underlying dermal hemorrhage.
describe the notable structures (arrows)
Leporid herpesvirus 4 infection of the skin from a rabbit, depicting a multinucleate syncytium and intranuclear inclusion bodies (arrows) in the follicular epithelium.
Cerebrum. Name the structures and causative agent.
Cerebrum from a rabbit with naturally acquired herpes
simplex virus encephalitis. Note the prominent intranuclear inclusion
bodies in neurons (arrows) and astroglia
1) Causative agent, genus
2) Usual means of transmission
3) Potential sequalae in NZW
1) Cottontail rabbit papillomavirus, Kappapapillomavirus
2) Insect vectors, e.g. mosquitos and ticks
3) squamous cell carcinoma
Describe. What is the most likely cause?
Solitary papilloma on the ear of a laboratory rabbit naturally infected with cottontail rabbit papilloma virus (CRPV).
1) causative agent
2) means of transmission
3) potential sequale
4) describe histology
1) rabbit oral papillomavirus
2) direct contact, including does to kits
3) none - no reports of malignant transformation
4) basophilic intranuclear inclusions and viral antigen in the stratun spinosum
1) tissue
2) arrow
3) cause
4) associated disease
1) Describe the lesions
2) causative agent
1) Mucopurulent conjunctivitis, periocular swelling, and
facial edema (myxomatosis)
2) myxoma virus
3) family Poxviridae, genus Leporipoxvirus
Tissue, arrows, cause
Intracytoplasmic inclusion bodies (arrows) in the
conjunctival epithelium of a rabbit with myxomatosis.
tissue, pathology, cause
Lymph node, depicting hypertrophy and hyperplasia of stellate myxoma cells and severe lymphocytic depletion.
Rabbit respiratory epithelium with intracytoplasmic inclusions (arrows). name the cause
Myxoma virus
Cause
related to
Rabbit (Shope) fibroma
myxoma virus
describe
arrows
cause
Skin of a Sylvilagus rabbit infected with Shope fibroma
virus. There is a dense network of fusiform to polyhedral fibroblasts in
the dermis, many of which contain prominent intracytoplasmic
inclusion bodies (arrows).
Organ, gross description, cause
Lungs from a wild Oryctolagus rabbit with acute rabbit
hemorrhagic disease (RHD) virus infection. There is marked pulmonary
edema with multifocal ecchymoses.
tissue, microscopic description, cause
Lung from a case of RHD in a feral Oryctolagus rabbit from Australia. Notemultiple intravascular thromboses
organ, gross description, cause
Liver from a domestic rabbit naturally infected with
RHD virus. Note the granular texture of the hepatic capsule and
accentuated lobular pattern.
tissue, microscopic description, cause
Liver from a rabbit experimentally infected with rabbit
hemorrhagic disease virus. Note the acute periportal and midzonal
hepatocellular necrosis.
tissue, microscopic description, cause
Small intestine from a juvenile rabbit with a natural case
of epizootic rotaviral enteritis. There is submucosal edema, with
blunting and fusion of villi. Enterocytes within crypts and on villi are
immature, indicative of regeneration.
tissue, microscopic description
Acute fibrinopurulent bronchopneumonia in a young
rabbit infected with Bordetella bronchiseptica. The terminal airway
and alveoli are flooded with fibrin-rich exudate.
Tissue
agent
distribution
stain
Lung of a rabbit naturally infected with cilia-associated
respiratory (CAR) bacillus. This organism colonizes the epithelium of
the larynx, trachea, and bronchi in the rabbit. Note the prominent
peribronchiolar lymphocytic infiltration (Warthin-Starry stain).
Organ
description
cause
Cecum from a rabbit with clostridial enteropathy. Note
the hemorrhage and the fibrinous exudate on the mucosal surface.
Cecum of rabbit with Clostridium spiriforme. Describe the tissues
Necrotizing typhlitis from a case of clostridial
enteropathy due to Clostridium spiroforme. Note the selective loss of
mucosal epithelium with relative sparing of crypts and submucosal
edema.
intestinal contents from a rabbit. Name the stain, name the organisms marked by the arrow.
Gram-stained smear of intestinal contents from a rabbit
with clostridial enteropathy, demonstrating the typical coiled
appearance of Clostridium spiroforme organisms (arrow).
Describe
cause?
Acute necrohemorrhagic typhlitis in a rabbit with
Tyzzer’s disease. Note ecchymotic hemorrhages on the serosa.
describe
hallmark sign of?
Multifocal hepatic necrosis in an adult rabbit with
Tyzzer’s disease.
describe
cause?
expected histologic lesions?
Acute gastric and intestinal tympany in a rabbit that
died acutely with epizootic rabbit enteropathy. The stomach and
intestine are distended with gas and fluid, but histologic lesions are
minimal or absent in this syndrome.
weanling rabbit with profuse diarrhea. cause?
Intestine from a weanling rabbit with profuse diarrhea
associated with acute infection with an attaching and effacing
enteropathogenic Escherichia coli (EPEC). Note the fluid content that
has leaked from an incision in the small intestine (arrow).
organism?
Stain?
Cecum from a case of acute coliform enteritis in a
weanling rabbit. The surface mucosa is densely populated with
attaching Escherichia coli (Warthin–Starry stain).
describe
Hemorrhagic enterotyphlocolitis in a suckling rabbit kit
due to Klebsiella oxytoca.
Hemorrhagic enterotyphlocolitis in a suckling rabbit kit
due to Klebsiella oxytoca.
describe
cause?
Histiocytic enteritis in a laboratory rabbit associated
with Lawsonia intracellularis infection. Note the marked thickening
and rugose appearance of the serosal surface of the small intestine.
Jejunum of rabbit
describe
cause?
Jejunum from a laboratory rabbit with histiocytic
enteritis due to Lawsonia intracellularis infection. Villi are shortened,
lacteals are dilated, crypts are hyperplastic, and the lamina propria and
submucosa are infiltrated with histiocytes and focal accumulations of
lymphocytes.
Rabbit intestinal mucosa. stain?
Organism?
Intestinal mucosa from a rabbit infected with Lawsonia
intracellularis. Note the dense argyrophilic populations of bacteria
within the apical cytoplasm of enterocytes (Warthin–Starry stain).
liver of near-term doe
describe lesion
cause?
New Zealand White doe that died near-term with acute
listeriosis. There are pinpoint-size foci of hepatitis. The externalized kit
(lower left) is intact, with no evidence of maceration
Tissue
describe lesion
Focal hepatitis from a case of listeriosis in a pregnant
doe. Note colonies of Gram-positive bacteria
organ
cause
Pulmonary tuberculosis in a rabbit infected with
Mycobacterium tuberculosis. Rabbits develop cavitary pulmonary
lesions with frequent dissemination to other organs.
Tissue
Causative agent
Small intestine of a wild Oryctolagus rabbit naturally
infected with Mycobacterium avium spp. paratuberculosis. The lamina
propria is densely infiltrated with histiocytes andmultinucleated giant cells.
Rabbit GALT histiocytes,
Name of organism
type of stain
Acid-fast organisms within histiocytes of the GALT of a
wild rabbit naturally infected with Mycobacterium avium spp.
paratuberculosis.
Describe lesion
causative agent
Turbinate atrophy associated with chronic rhinitis due to
Pasteurella multocida infection. Note the loss of turbinates in the
affected (top) compared to the normal control rabbit (bottom).
Describe lesion
Fibrinohemorrhagic bronchopneumonia and pleuritis in
a rabbit with peracute pulmonary pasteurellosis. Fibrinous exudate is
present on the pleural surface.
Organ
describe lesions
Pyometra in an adult doe associated with chronic
Pasteurella multocida infection. There is asymmetric distention of the
uterine horns, and the fallopian tubes are distended with purulent
exudate (right arrow). Small abscesses are scattered on the serosa (left
arrows).
Expected lesions in adult rabbits
histo
DDx
Systemic staphylococcosis with focal suppurative lesions can occur in adult rabbits
Staphylococcal mastitis: swollen, red areas, induration of overlying skin, chronic abscess
Respiratory tract: mucopurulent rhinitis, bronchopneumonia, and/or abscessation of the lung
Histo: focal suppurative lesions in affected organs, w/ Gram + bacterial colonies
DDX: pasteurellosis, Tyzzer’s disease, and listeriosis
Transmission
Age predilection
Treponema paraluis-cuniculi (formerly T. cuniculi) is a spirochete
◦Occurs occasionally in lab rabbits, has been documented in wild rabbits in Britain
◦Seldom detected on cursory examination
Venereal route is the most important means of spread, but extragenitalcontact transmission may occur
Young animals may develop the disease following contact with an infected dam
Young rabbits have been shown to be relatively resistant to the infection
Describe lesion.
causatuve agent
Multifocal caseation necrosis in the liver of a rabbit
naturally infected with Yersinia pseudotuberculosis.
Tissue
Stain
Organism
Lung from a rabbit kit with pulmonary aspergillosis,
illustrating fungal hyphae (methenamine silver stain).
Other organs affected?
Kidney
Lung
Liver
Heart
Cerebrum
Route of transmision in this case?
Breed?
Phacoclastic uveitis and cataract formation is believed to follow transplacental infection
◦Common among dwarf rabbits, but other breeds may be affected
Stain?
Tissue?
Organism?
Encephalitozoon spores within renal tubular
epithelium and tubular lumen of a rabbit with chronic
encephalitozoonosis (Brown and Brenn stain).
Small intestine from a juvenile rabbit.
Describe lesions
with acute
coccidiosis. Enterocytes contain large numbers of micro- and
macrogametocytes and oocysts.
Liver from a juvenile rabbit.
Describe lesion
causative agent
Liver from a juvenile rabbit with florid hepatic
coccidiosis. In addition to the raised linear hepatic lesions, representing
involved bile ducts, the gall bladder and common bile duct are dilated
and contain flocculent material.
causative agent
describe histo
Hepatic bile duct of a rabbit with chronic hepatic
coccidiosis, featuring proliferative cholangitis, periportal fibrosis, and
inflammation. Bile ductular epithelium contains large numbers of
microgametocytes, macrogametocytes, and oocysts.
Organ
Organism
Opened cecum from a domestic rabbit with Passalurus
ambiguus (pinworm) infestation.
Name of organism
Describe pathogenesis of lesion
Multiple Taenia pisiformis cysticerci (arrow) within the
peritoneal cavity of a rabbit.
Cysticerosis
◦Intermediate host stage is known as Cysticercus pisiformis
◦Ingest eggs à larvae hatch in the small intestine and migrate to the liver and blood stream
◦Cysticerci develop in the liver for a few weeks à migrate to the peritoneal cavity, where they attach to serosal surfaces
Causative agent
New Zealand White rabbit with Cheyletiella
parasitovorax infestation. Pruritus has resulted in patchy hair loss and
cutaneous erythema.
Life cycle of causative agent
Psoroptes cuniculi
Obligate, nonburrowing parasites that chew and pierce the epidermal layers of the external ear, evoking a marked inflammatory response
Normally spends its entire life span in the external ear of the rabbit
Life cycle (egg to egg) is usually completed in around 3 wks
Describe lesion
Ears of the rabbit with scabies in the previous figure,
depicting severe hyperkeratosis.
Tissue
Organism
Marked hyperkeratosis with numerous Sarcoptes mites
embedded in the keratinized debris. Note the spongiform appearance of
the keratinized epithelium due to tunneling by mites.
Risk factors
Variable morbidity, but can be high particularly in during postweaning period
High mortality rate
Rabbits 7–10 wks old are most often affected, but rabbits 5 wks to adults may be involved in outbreaks
Dietary factors have frequently been implicated in the pathogenesis
◦Relatively uncommon prior to the feeding of high-energy commercial rations
◦Rabbits fed high-carbohydrate/ low-fiber diet have a higher incidence of the ME than those fed diets high in fiber
describe lesion
Dx
massive discharge of mucin from goblet cells, with minimal or no inflammatory response
◦Colonic crypts and the lumen are distended with mucus/mucous plugs
◦Lesions are usually minimal to absent in the cecum
Mucoid enteropathy
Predisposing factors
excessive grooming and hair chewing due to boredom, insufficient dietary roughage, poor gastric motility, and a sedentary lifestyle (decreased gastric motility)
“Outbreaks” of trichobezoars have been seen in lab rabbits raised in cold climates, and then introduced to warm indoor housing
Associated with
chronic exfoliative dermatosis and sebaceous adenitis.
Associated with autoimmune hepatitis, thymoma, and cutaneous lymphoma
Predisposing factors
Associated organism
Most commonly seen in heavy, mature adults
Predisposing Factors: poor sanitation, trauma from poor-quality, wire-bottom cages, and hereditary predisposition
Staphylococcus aureus is the most frequent bacterium isolated from lesions
Most common location
Fracture site (or luxation) is usually the lumbosacral region (L7)
Clinical presentation
Observed in nonpregnant multiparous does
Associated with persistent urogenital bleeding
Necropsy: clotted blood present in the uterine lumen, w/ multiple blood-filled endometrial varices that consist of dilated, thin-walled veins
Varices may rupture and bleed periodically into the uterine lumen, with subsequent hematuria
underlying cause
metabolic influences
Intestinal absorption of calcium occurs in direct proportion to dietary intake. Rabbits fed high-calcium diets e.g. alfalfa that become sick can have impaired renal absorption/excretion
◦Renal calcium resorption and excretion are in proportion to dietary intake, and regulated by parathyroid hormone, calcitonin, and vitamin D
When the resorptive capacity of the kidney is exceeded, calcium precipitates in the alkaline urine as calcium carbonate monohydrate, anhydrous calcium carbonate, and ammonium magnesium phosphate
Renal interstitial amyloidosis in a chronically
immunized adult New Zealand White rabbit.
Associated with
Other organs affected
most likely in older hyperimmunized rabbits, those w/ chronic infections (pododermatitis, pyometra), or experiment. induced
Tissue
Condition
Cause
Condition
Cause
Hypercalcemic arteriorsclerosis
excessive calcium/renal overload or impairment leads to hypercalcemoia. results in metastatic mineralization of blood vessels and other tissues, including pulmonary interstitium, and kidneys (nephrocalcinosis)
Hepatic lipidosis in rabbits
Mechainism
Models
Rabbits are unable to increase excretion of sterols
in the bile in response to high cholesterol in the diet, resulting in
hypercholesterolemia, hepatic lipidosis, and icterus.
NZWs fed high-cholestreol diet. hepatopathy limits long-term experiments
Watanabe heritable hyperlipidemic syndrome homozygous rabbits - spontaneous
Copper toxicosis
Signs of acute toxicity
Histo findings - organ, stain
hemolytic anemia w/ intravasc hemolysis, splenic erythrophagocytosis,
Hepatocytes and Kupffer cells contained blue-green cytoplasmic granules that stain positive w/ rhodanine stain
Age of onset
Underlying cause
Genetics
First few weeks of life to 3–5 months of age
Primary defect = absence or underdevelopment of the outflow channels, with incomplete cleavage of the iridocorneal angles
Autosomal recessive allele, with incomplete penetrance
Genetics
condition
Maxillary brachygnathia (erroneously termed mandibular prognathism)à most common genetic disorder in domestic rabbits
Autosomal recessive
Morphologic changes
coxofemoral subluxation, shallow acetabula, lateral patellar luxation, valgus deformity, and bowing of the tibia
Incidence
2–3 yrs à ~4%, 5–6 yrs à ~80%
Kidneys from a young rabbit. Multiple pale nodular masses are visible in the cortex,
Diagnosis
Lymphoma
Most common malignancy in juvenile and young adult rabbits
pale kidneys w/ irregular cortical surfaces (PATHOGNOMONIC)
Most common tumor type
carcinomas
